Effects of deformation and annealing on the microstructures and properties of a nonequiatomic Co₂₉Cr₂₉Fe₂₉Ni_12.5W_0.5 high-entropy alloy

Nonequiatomic Co₂₉Cr₂₉Fe₂₉Ni_12.5W_0.5 high-entropy alloys (HEAs) were prepared by vacuum induction melting and subsequent mechanical processing. The HEA with face-centered cubic and few hexagonal close-packed structure phases exhibited outstanding mechanical properties. After annealing at 725 °C, the yield strength and fracture elongation were 1.13 GPa and 24.3%, respectively. The outstanding mechanical properties were attributed to the addition of the W element and ultrafine grain structure. The results demonstrated that dislocation slip, stacking faults, and nano-twins governed the deformation mechanism, and these defects were responsible for the decrease in the work-hardening rate during the deformation processing in the 725°C-annealed alloy.